Patent GB-549850-A (GB)
Title: Improvements in or relating to tire shaping apparatus
IPC: B29D30/36
Filed: 1941-03-18
Abstract: 549,850. Moulding wheel tyres ; electric motor control systems. FIRESTONE TIRE & RUBBER CO. March 18, 1941, No. 3722. Convention date, Aug. 3, 1940. [Class 87 (ii)] [Also in Group XXXVII]  Relates to tyre-shaping apparatus of the type in which a flat band is shaped to tyre form by fluid pressure applied to its interior while it is confined between an annular bottom plate 19 and a plate 26 provided on the lower end of a vertically-reciprocable cylinder 24, an expansible core 86 being concurrently introduced into the tyre. Operation :-(1) The core is hung on a hook 45 which is vertically reciprocable within the cylinder, and an inflating hose carried on the inside of the cylinder is attached to the core. (2) The hook rises, taking the core with it. (3) An annular unvulcanized rubber band 85 is positioned on the plate 19. (4) The cylinder descends. During this descent, (a) compressed air is admitted to the' tyre band via pipe 21, (b) the hook, with its core, starts to descend and (c) compressed air is admitted to the core. (5) The cylinder stops, for 4 seconds, in the position shown in Fig. 15. (6) The cylinder resumes its descent and finally stops in the position shown in Fig. 16. During (5) and (6),  (a), (b) and (c) continue. (7) As the cylinder stops, air is allowed to escape from the band and core. (8) The cylinder rises, without dwell,  to its initial position, taking the hook (minus the core) with it. When moulding large tyres the core is first exhausted of air, and drawn into the cylinder, and the cylinder is fully lowered (to shape the tyre band and provide more room for the core) and then raised to its intermediate position. The core is then ejected from the descending cylinder as described above. Fixed on the top of the cylinder is a pedestal 28 having six cams 71 ... 76. As the cylinder reciprocates, these cams actuate electrical switches 77 ... 82. The cylinder is reciprocated, via racks 29 and pinions 30, by an electric motor 38. The' hook is adjustably mounted on a piston 42 carried by a hollow stem 50 secured to a nut 47 which is impelled by rotation of a feed screw 52 driven by an electric motor 55. The motor 55 also rotates cams 60, 61, 62 which actuate switches 64, 65, 67 respectively. Electrical control:-Fig. 12 shows the wiring diagram for the hook control and cylinder control. (a) With the core on the hook, the operator closes a switch (not shown) which closes switches 105 (preparing the circuit for automatic control) and opens (" manual control ") switches 104. (b) Operator presses button 95 to energize " hook up " relay 148 which starts motor 55 ; relay 148 closes switch 150 to form a hold-in circuit. As the hook ascends, switch 67 closes, thus preparing " hook down " relay 155. At upper limit of travel, switch 65 opens and motor 55 stops. (c) With tyre band on plate 19, operator presses button 91 to energize " cylinder down" relay 114 which starts motor 38 ; relay 114 closes switch 119 to form a hold-in circuit. Descent of the cylinder first closes switch 77, thus preparing " cylinder up " circuit, then reverses switch 80 (Fig. 7) to admit compressed air to tyre band, then closes switch 82 to energize hook down " relay 155 which starts motor 55 to lower the hook (relay 155 closing switch 158 to form a hold-in circuit), then closes switch 81 to admit compressed air to the core, and finally reverses switch 78 to halt the cylinder. Reversal of switch 78 energizes time relay 120 which, after 4 seconds, closes switch 121, thus re-energizing relay 114, the cylinder then resuming descent. Just after resumption, cam 72 moves away from switch 78, which thereupon reverts to the position shown and time relay 120 is deenergized, opening switch 121 ; during reversal of switch 78, relay 120 is fed by a conductor 123 from a contact of switch 121, which contact is broken as soon as switch 78 is fully reversed. Just before the cylinder reaches its lowermost position (Fig. 16) switches 80 and 81 are reversed to evacuate air from tyre and core. At said lowermost position switch 67 opens, de-energizing relay 155 and stopping motor 55, and switch 79 reverses, de-energizing relay 114 and energizing relay 126 which immediately starts motor 38 to raise the cylinder and hook ; relay 126 closes switch 129 to form a hold-in circuit. At the upper and lower limits of travel of the cylinder and hook dynamic braking is effected by putting 115 v. D.C. across the rotors of the motors. Thus, when relays 114 and 126 are de-energized, they close switches 136 and 137, respectively to energize cylinder motor braking coil 139 and time relay 140. The relay 140 first opens switch 110, cutting off current to the cylinder control circuits, and then, after a brief interval, opens switch 138, thereby de-energizing coil 139 and removing the braking current from the motor 38. Similarly, the hook motor circuit has a braking coil 169 and time relay 166 which opens switch 145. For manual operation, switches 105 are open, switches 104 are closed, and the cylinder and hook are raised and lowered by means of button switches 91, 90, 95 and 96 respectively. Specification 419,244 is referred to.